Field-effect controlled power switching structures such as trench Metal Oxide Semiconductor Field Effect Transistors (trench MOSFETs) have been used for various applications including but not limited to switches in power supplies and power converters, e.g., half-bridges.
A key figure for trench MOSFETs which is to be optimized with regard to switching losses and switching speed is the active area-independent product called the Figure of Merit (FOM) which equals the product of the on-state resistance R(DS)ON and the gate charge QG to turn on the transistor. The gate charge QG depends on the gate-drain capacitance CGD.
In view of meeting the demands on electrical characteristics of trench MOSFETs, it is desirable to reduce both their on-state resistance R(DS)ON and their gate-drain capacitance CGD, i.e., to reduce the FOM.